"What a splendid field it is for new expeditions," wrote 19th-century mountaineer Frederick Chapin. Gold and silver drew mining expeditions in the early days. Today some 26 million visitors a year make excursions to the highest state. As ski resorts and tourist centers expand, wildlife habitat and the "splendid field" suffer. In Aspen and Telluride particulate pollution, mainly from wood-burning stoves, can be worse than in Denver; regulations limit fireplaces in new homes.

Pueblo, once dependent on steel, has broadened its industrial base; the city is also the gateway to rafting and camping in the southern mountains. Colorado's economy, long reliant on energy and minerals, would be in the doldrums without tourism, a $7 billion industry. Near Denver, energy capital of the mountain West, the Rocky Flats weapons plant, which once pumped 300 million dollars a year into state coffers, no longer manufactures nuclear arms. An environmental cleanup of the site—with a $7 billion price tag—is nearing completion.